Bump rexml from 3.3.9 to 3.4.2 in /docs

Bumps [rexml](https://github.com/ruby/rexml) from 3.3.9 to 3.4.2.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](ruby/rexml@v3.3.9...v3.4.2)

---
updated-dependencies:
- dependency-name: rexml
  dependency-version: 3.4.2
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

docs/Gemfile

@@ -28,4 +28,4 @@ gem "jekyll-redirect-from", "~> 0.16"
 # This resolves a build issue on Apple Silicon.
 # See: https://issues.apache.org/jira/browse/SPARK-38488
 gem "ffi", "~> 1.15"
-gem "rexml", "~> 3.3.9"
+gem "rexml", "~> 3.4.2"

docs/Gemfile.lock

@@ -62,7 +62,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rexml (3.3.9)
+    rexml (3.4.2)
     rouge (4.5.2)
     safe_yaml (1.0.5)
     sass-embedded (1.89.2)
@@ -80,7 +80,7 @@ DEPENDENCIES
   ffi (~> 1.15)
   jekyll (~> 4.4)
   jekyll-redirect-from (~> 0.16)
-  rexml (~> 3.3.9)
+  rexml (~> 3.4.2)
 
 BUNDLED WITH
    2.4.22